Fig. 3

Bacterial phylotypes which are significantly enriched in healthy (a) or necrotic (c) Eunicella gazella tissue. For comparison, the respective abundances of some of these phylotypes (OTUs) in the other octocoral species, sediment, and seawater are shown in b and d. Bars represent average proportions (%) ± standard errors. Paired t-tests (a and c) or one-way ANOVAs (b and d) followed by Bonferroni tests were used to check for significant differences between sample groups. Statistical significance was established at P-values ≤ 0.05. Letters or asterisks above error bars indicate significant differences (*P ≤ 0.05; **P ≤ 0.01; ***P ≤ 0.001). Respective P-values are presented in the graphs. All phylotypes shown here are among the top ten phylotypes respectively enriched in healthy or in necrotic E. gazella tissue (Additional file 2: Table S4b,c) that contributed most to the dissimilarities between these microbiomes, as revealed by SIMPER and “Indicspecies” analyses